From: Li Zefan <lizefan@huawei.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>, Glauber Costa <glommer@openvz.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Johannes Weiner <hannes@cmpxchg.org>,
LKML <linux-kernel@vger.kernel.org>,
Cgroups <cgroups@vger.kernel.org>,
linux-mm@kvack.org, Michal Hocko <mhocko@suse.cz>
Subject: [PATCH v4 2/9] memcg, kmem: fix reference count handling on the error path
Date: Fri, 14 Jun 2013 09:53:59 +0800 [thread overview]
Message-ID: <51BA77B7.5030405@huawei.com> (raw)
In-Reply-To: <51BA7794.2000305@huawei.com>
From: Michal Hocko <mhocko@suse.cz>
mem_cgroup_css_online calls mem_cgroup_put if memcg_init_kmem
fails. This is not correct because only memcg_propagate_kmem takes an
additional reference while mem_cgroup_sockets_init is allowed to fail as
well (although no current implementation fails) but it doesn't take any
reference. This all suggests that it should be memcg_propagate_kmem that
should clean up after itself so this patch moves mem_cgroup_put over
there.
Unfortunately this is not that easy (as pointed out by Li Zefan) because
memcg_kmem_mark_dead marks the group dead (KMEM_ACCOUNTED_DEAD) if it
is marked active (KMEM_ACCOUNTED_ACTIVE) which is the case even if
memcg_propagate_kmem fails so the additional reference is dropped in
that case in kmem_cgroup_destroy which means that the reference would be
dropped two times.
The easiest way then would be to simply remove mem_cgrroup_put from
mem_cgroup_css_online and rely on kmem_cgroup_destroy doing the right
thing.
Cc: <stable@vger.kernel.org> # 3.8+
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
mm/memcontrol.c | 8 --------
1 file changed, 8 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0bacc0d..b5ec4da 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6325,14 +6325,6 @@ mem_cgroup_css_online(struct cgroup *cont)
error = memcg_init_kmem(memcg, &mem_cgroup_subsys);
mutex_unlock(&memcg_create_mutex);
- if (error) {
- /*
- * We call put now because our (and parent's) refcnts
- * are already in place. mem_cgroup_put() will internally
- * call __mem_cgroup_free, so return directly
- */
- mem_cgroup_put(memcg);
- }
return error;
}
--
1.8.0.2
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2013-06-14 1:57 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-14 1:53 [PATCH v4 0/9] memcg: make memcg's life cycle the same as cgroup Li Zefan
2013-06-14 1:53 ` [PATCH v4 1/9] Revert "memcg: avoid dangling reference count in creation failure." Li Zefan
2013-06-14 1:53 ` Li Zefan [this message]
2013-06-14 1:54 ` [PATCH v4 3/9] memcg: use css_get() in sock_update_memcg() Li Zefan
2013-06-14 1:54 ` [PATCH v4 4/9] memcg: don't use mem_cgroup_get() when creating a kmemcg cache Li Zefan
2013-06-14 1:54 ` [PATCH v4 5/9] memcg: use css_get/put when charging/uncharging kmem Li Zefan
2013-06-28 22:59 ` Andrew Morton
2013-06-14 1:55 ` [PATCH v4 6/9] memcg: use css_get/put for swap memcg Li Zefan
2013-06-14 1:55 ` [PATCH v4 7/9] memcg: don't need to get a reference to the parent Li Zefan
2013-06-14 1:55 ` [PATCH v4 8/9] memcg: kill memcg refcnt Li Zefan
2013-06-14 1:56 ` [PATCH v4 9/9] memcg: don't need to free memcg via RCU or workqueue Li Zefan
2013-06-19 1:29 ` [PATCH v4 0/9] memcg: make memcg's life cycle the same as cgroup Li Zefan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=51BA77B7.5030405@huawei.com \
--to=lizefan@huawei.com \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=glommer@openvz.org \
--cc=hannes@cmpxchg.org \
--cc=kamezawa.hiroyu@jp.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.cz \
--cc=tj@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).